NPCs currently don't hold inventory. At all, actually. This makes it somewhat difficult for us to keep track of whether or not they can be stolen from (particularly how much money they have left) and inventory-related issues such as dropping weapons, stealing player items, etc. NPCs simply don't function like anything else.

Other data, such as objects, players, and rooms, can all hold objects and it is likely that NPCs will support it eventually as well. When they do, it is planned that the Barbarian Disarm ability work against them as well.